This is The Long Result by John Brunner. There are a number of elements that match your description;
- Planet called Starhome - Check.
- Aliens called 'Relgans(?)' - Check (Regulans, actually)
- Book cover with rocket - Check
- Blue aliens - Check
- Legs that bend the wrong way - Check (described as "back-bent")
- Anti-hol - Check (described as "Anti-Alcohol")
